Management of an electric power generation and storage system

ABSTRACT

In one technique of the present invention, DC electric power from a DC bus is inverted to provide AC electricity to one or more electrical loads, and AC power from a power generating device is rectified to provide a first variable amount of electric power to the DC bus. This technique also includes determining power applied to the electrical loads, and dynamically controlling the amount of power supplied from the power generating device and an electrical energy storage device in response to the power applied to the loads.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 11/809,751, filed Jun. 1, 2007, U.S. patentapplication Ser. No. 12/462,891, filed Aug. 11, 2009, U.S. patentapplication Ser. No. 12/005,674, filed Dec. 28, 2007, U.S. patentapplication Ser. No. 12/006,075, filed Dec. 28, 2007, U.S. patentapplication Ser. No. 11/809,607, filed Jun. 1, 2007, and U.S. patentapplication Se. No. 11/809,768, filed Jun. 1, 2007, all of which arehereby incorporated by reference each in its entirety.

BACKGROUND

The present invention relates to electric power systems, and moreparticularly, but not exclusively, relates to management of electricpower provided by a system including an electric energy storage deviceand one or more other electric power sources.

Many electrical power system configurations include an energy storagedevice, such as a battery or battery bank, and one or more otherelectric power sources. Sometimes, at least one of these sources is ofan adjustable and/or non-continuously operating type, like a variablespeed generator—to name one example. Notably, steady state load demandis typically low relative to generator power capacity. In contrast,generator selection is often driven by peak power requirements that canbe transitory in nature. Such generators may be considered “oversized”during the majority of time they are used. However, if peak loads cansomehow be otherwise accommodated, there might be an opportunity toreduce generator size based on “typical” electrical loading. For furtherdescription, see commonly owned U.S. patent application Ser. No.11/809,751 (previously incorporated by reference). In some such systems,the generator is selected with sufficient capacity to charge the storagedevice at the same time it supplies power to electrical loads undercertain conditions.

A generator set including a variable-speed generator, energy storagedevice, and like poses significant regulation and controlchallenges—especially when provided in a vehicle—such as a motor coach,trailer, camper, marine vessel, or the like. Moreover, if a differenttype of adjustable/discontinuous electric energy source is included,either with or without a variable-speed generator, similar challengesarise. Thus, there is an ongoing demand for further contributions inthis area of technology.

SUMMARY

One embodiment of the present invention includes a unique techniqueinvolving electric power generation, storage, delivery, and/or control.Other embodiments include unique methods, systems, devices, andapparatus involving the generation, storage, delivery, and/or control ofelectric power. Further embodiments, forms, features, aspects, benefits,and advantages of the present application shall become apparent from thedescription and figures provided herewith.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagrammatic view of a vehicle carrying an electric powergeneration system including a genset.

FIG. 2 is a schematic view of circuitry included in the system of FIG.1.

FIG. 3 is a further diagram directed to the circuitry of FIG. 2.

FIG. 4 is a control system diagram for inverter operation of thecircuitry of FIG. 2 to source controlled AC electric power from theelectric power generation system.

FIG. 5 is a control system diagram for converter operation of thecircuitry of FIG. 2 to store electric energy from an external source.

FIG. 6 is a flowchart of one procedure for operating the system of FIG.1 in different power boost operating states.

FIG. 7 is a flowchart for handling different types of power transientsduring the execution of the procedure illustrated in FIG. 5, and furtherrelates to different power boost operations.

FIG. 8 is a schematic block diagram of another embodiment of a powergeneration system.

FIG. 9 is a schematic block diagram of one embodiment of a first type ofpower source.

FIG. 10 is a schematic block diagram of another embodiment of a firsttype of power source.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described embodiments, and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

FIG. 1 illustrates vehicle 20 in the form of a motor coach 22. Motorcoach 22 includes interior living space 24 and is propelled by coachengine 26. Coach engine 26 is typically of a reciprocating piston,internal combustion type. To complement living space 24, coach 26carries various types of electrical equipment 27, such as one or moreair conditioner(s) 88. Equipment 27 may further include lighting,kitchen appliances, entertainment devices, and/or such different devicesas would occur to those skilled in the art. Coach 22 carries mobileelectric power generation system 28 to selectively provide electricityto equipment 27. Correspondingly, equipment 27 electrically loads system28. In one form, various components of system 28 are distributedthroughout vehicle 20—being installed in various bays and/or otherdedicated spaces.

System 28 includes two primary sources of power: Alternating Current(AC) power from genset 30 and Direct Current (DC) power from electricalenergy storage device 70. Genset 30 includes a dedicated engine 32 andthree-phase AC generator 34. Engine 32 provides rotational mechanicalpower to generator 34 with rotary drive member 36. In one arrangement,engine 32 is of a reciprocating piston type that directly drivesgenerator 34, and generator 34 is of a permanent magnet alternator (PMA)type mounted to member 36, with member 36 being in the form of a driveshaft of engine 32. In other forms, generator 34 can be mechanicallycoupled to engine 32 by a mechanical linkage that provides a desiredturn ratio, a torque converter, a transmission, and/or a different formof rotary linking mechanism as would occur to those skilled in the art.Operation of engine 32 is regulated via an Engine Control Module (ECM)(not shown) that is in turn responsive to control signals from controland inverter assembly 40 of system 28.

The rotational operating speed of engine 32, and correspondinglyrotational speed of generator 34 varies over a selected operating rangein response to changes in electrical loading of system 28. Over thisrange, genset rotational speed increases to meet larger power demandsconcomitant with an increasing electrical load on system 28. Genset 30has a steady state minimum speed at the lower extreme of this speedrange corresponding to low power output and a steady state maximum speedat the upper extreme of this speed range corresponding to high poweroutput. As the speed of genset 30 varies, its three-phase electricaloutput varies in terms of AC frequency and voltage.

Genset 30 is electrically coupled to assembly 40. Assembly 40 includespower control circuitry 40 a to manage the electrical power generatedand stored with system 28. Circuitry 40 a includes three-phase rectifier42, variable voltage DC power bus 44, power bridge 46, charge and boostcircuitry 50, and processor 100. Assembly 40 is coupled to storagedevice 70 to selectively charge it in certain operating modes and supplyelectrical energy from it in other operating modes via circuitry 50 asfurther described hereinafter. Assembly 40 provides DC electric power tothe storage device one or more motor coach DC loads 74 with circuitry 50and provides regulated AC electric power with power bridge 46. ACelectric loads are supplied via AC output bus 80. When power is beingsourced to bus 80 from genset 30 and/or device 70 via bus 44, powerbridge 46 is controlled to operate as a DC to AC inverter as furtherdescribed in connection with FIG. 4 hereinafter. Bus 80 is coupled to ACpower transfer switch 82 of system 28. One or more coach AC electricalloads 84 are supplied via switch 82. System 28 also provides loaddistribution 86 from bus 80 without switch 82 intervening therebetween.

As shown in FIG. 1, switch 82 is electrically coupled to external ACelectrical power source 90 (shore power). It should be appreciated thatshore power generally cannot be used when vehicle 20 is in motion, maynot be available in some locations; and even if available, shore poweris typically limited by a circuit breaker or fuse. When power fromsource 90 is applied, genset 30 is usually not active. Transfer switch82 routes the shore power to service loads 84, and those supplied byinverter load distribution 86. With the supply of external AC power fromsource 90, assembly 40 selectively functions as one of loads 84,converting the AC shore power to a form suitable to charge storagedevice 70. For this mode of operation, power bridge 46 is controlled tofunction as an AC to DC converter as further described in connectionwith FIG. 5 hereinafter.

Assembly 40 further includes processor 100. Processor 100 executesoperating logic that defines various control, management, and/orregulation functions. This operating logic may be in the form ofdedicated hardware, such as a hardwired state machine, programminginstructions, and/or a different form as would occur to those skilled inthe art. Processor 100 may be provided as a single component, or acollection of operatively coupled components; and may be comprised ofdigital circuitry, analog circuitry, or a hybrid combination of both ofthese types. When of a multi-component form, processor 100 may have oneor more components remotely located relative to the others. Processor100 can include multiple processing units arranged to operateindependently, in a pipeline processing arrangement, in a parallelprocessing arrangement, and/or such different arrangement as would occurto those skilled in the art. In one embodiment, processor 100 is aprogrammable microprocessing device of a solid-state, integrated circuittype that includes one or more processing units and memory. Processor100 can include one or more signal conditioners, modulators,demodulators, Arithmetic Logic Units (ALUs), Central Processing Units(CPUs), limiters, oscillators, control clocks, amplifiers, signalconditioners, filters, format converters, communication ports, clamps,delay devices, memory devices, and/or different circuitry or functionalcomponents as would occur to those skilled in the art to perform thedesired communications. In one form, processor 100 includes a computernetwork interface to facilitate communications using the Controller AreaNetwork (CAN) standard among various system components and/or componentsnot included in the depicted system, as desired.

Referring additionally to the schematic circuit view of FIG. 2 and thecontrol flow diagram of FIG. 3, selected aspects of system 28 arefurther illustrated; where like reference numerals refer to likefeatures previously described. In FIG. 3, blocks formed with heavierline weighting correspond to hardware-implemented functionality, andblocks formed with lighter line weighting correspond tosoftware-implemented functionality provided by programming of processor100. Assembly 40 includes Electromagnetic Interference (EMI) filter 38coupled to three-phase rectifier 42. In one form, rectifier 42 isimplemented with a standard six diode configuration applicable tothree-phase AC-to-DC conversion. Rectifier 42 receives the EMI-filtered,three-phase AC electric power output from genset 30 when genset 30 isoperational. Filter 38 removes certain time varying characteristics fromthe genset output that may result in undesirable inference and rectifier42 converts the filtered three-phase AC electric power from genset 30 toa corresponding DC voltage on bus 44.

At least one capacitor 45 is coupled across DC bus 44 to reduce residual“ripple” and/or other time varying components. The DC voltage on bus 44is converted to an AC voltage by power bridge 46 in response to powercontrol logic 104 of processor 100 when power is sourced to bus 80 frombus 44. Power bridge 46 is of a standard H-bridge configuration withfour Insulated Gate Bipolar Transistors (IGBTs) that is controlled byPulse Width Modulated (PWM) signals from processor 100. In other forms,power bridge 46 can be comprised of one or more other switch types suchas field effect transistors (FETs), gated thyristors, silicon controlledrectifiers (SCRs), or the like. The PWM control signals from logic 104selectively and individually drive the gates/switches of power bridge46. Typically, these control signals are input to intervening powerdrive circuitry coupled to inverter gates, and the control signals areisolated by opto-isolators, isolation transformers, or the like. Powercontrol logic 104 includes a Proportional-Integral (PI) controller tosynthesize an approximate sinusoidal AC waveform. Sensing arrangement 49includes AC voltage sensor 46 a and AC current sensor 46 b. Powercontrol logic 104 receives AC voltage (VAC) from voltage sensor 46 a andAC current (IAC) from current sensor 46 b that correspond to the powerdelivered to bus 80 from power bridge 46. The VAC and IAC inputs tologic 104 are utilized as feedback to generate the sinusoidal waveformfor the output power with a PI controller.

FIG. 4 describes in greater detail a DC to AC inverter control system204 defined with logic 104 and corresponding circuitry 104 a; where likereference numerals refer to like features. Power bridge 46 is comprisedfour IGBTs 104 a (more specifically designated U, V, X, and Y) each witha corresponding free-wheeling diode 104 c. Sensors 46 a and 46 b monitorVAC and IAC of power bridge 46. Via control loop 215 a, VAC from sensor46 a is input to control operator 216 a that applies the transferfunction H_(v)(s). The DC voltage from DC bus 44 designated as signalVdc, is also input to operator 216 a. The output from operator 216 a isprovided to the negative input of summation operator 217 a. The positiveinput of summation operator 217 a receives a target AC voltage,designated as signal Vac, from which the negative input is subtracted toprovide signal Verr. Verr is input to control operator 218 a thatapplies the transfer function G_(v)(s) to provide an output to apositive input of summation operator 217 c. Via control loop 215 c, IACfrom sensor 46 b is input to control operator 216 c that applies thetransfer function H_(i)(s). The output of operator 216 c is provided tothe negative input of summation operator 217 c to be subtracted fromVerr. The output of summation operator 217 c is designated as signalierr, and is input to control operator 218 b. Operator 218 b applies thetransfer function G_(i)(s) to provide the voltage drive signal, Vdrive,to the IGBTs 104 a of power bridge 46. It should be appreciated thatcontrol system 204 and corresponding operators/logic can be implementedwith hardware, software, firmware, or a combination of these.

The VAC and IAC inputs from sensors 46 a and 46 b, respectively are alsoused to calculate power properties required to control sharing functionsfor the overall system. System control logic 110 receives AC poweroutput information from inverter control logic 104. This information canbe used to determine system power, and is used to compare with the powerdelivery capacity of genset 30 and device 70 to regulate certainoperations described hereinafter. Furthermore, logic 110 uses this ACoutput information to determine whether a transient power conditionexists that warrants consideration in such operations.

Inductor 47 a and capacitor 47 b provide further filtering andconversion of the power bridge 46 output to a desired AC power waveform.EMI filter 48 provides interference filtering of the resulting AC powerwaveform to provide a regulated single-phase AC power output on bus 80.In one nonlimiting example, a nominal 120 VAC, 60 Hertz (Hz) output isprovided on bus 80, the genset three-phase output to rectifier 42 variesover a voltage range of 150-250 volts AC (VAC) and a frequency range of200-400 Hertz (Hz), and the variable voltage on DC bus 44 is between 200and 300 volts DC (Vdc).

In addition to logic 104, processor 100 includes genset power requestcontrol logic 102 to regulate rotational speed of genset 30 relative tosystem 28 operations. Logic 102 provides input signals to genset 30 thatare representative of a requested target load to be powered by genset30. Genset governor 103 of genset 30 responds to logic 102 to adjustengine rotational speed, which in turn adjusts rotational speed ofgenerator 34. Control by logic 102 is provided in such a manner thatresults in different rates of genset speed change(acceleration/deceleration) depending on one or more conditions (liketransients), as more fully explained in connection with FIGS. 6 and 7hereinafter.

In one particular form, governor 103 is implemented in an Engine ControlModule (ECM) included with genset 30 that communicates with processor100 over a CAN interface. Alternatively or additionally, at least aportion of governor 103 can be included in assembly 40. Speed controllogic 102 is responsive to system control logic 110 included in theoperating logic of processor 100, and an engine speed feedback signalprovided by engine speed sensor 112. Speed adjustment with logic 102 canarise with changes in electrical loading and/or charge or boostoperations of device 70, as further described hereinafter. In turn,logic 102 provides control inputs to charge and power boost controllogic 106.

Controllable DC-to-DC converter 60 is electrically coupled to DC bus 44and electrical energy storage device 70. In FIG. 2, device 70 is morespecifically illustrated in the form of electrochemical battery device75 as shown in FIG. 2. Electrical current flow between device 70 andconverter 60 is monitored with current sensor 76 and DC voltage ofdevice 70 is monitored at node 78. In one embodiment, more than onecurrent sensor and/or current sensor type may be used (not shown). Forexample, in one arrangement, one sensor may be used to monitor currentof device 70 for power management purposes (such as a Hall effect sensortype), and another sensor may be used in monitoring various chargingstates (such as a shunt type). In other embodiments, more or fewersensors and/or sensor types may be utilized.

Converter 60 provides for the bidirectional transfer of electrical powerbetween DC bus 44 and device 70. Converter 60 is used to charge device70 with power from DC bus 44, and to supplement (boost) power madeavailable to DC bus 44 to service power demand on bus 80. Converter 60includes DC bus interface circuitry 54 and storage interface circuitry64 under the control of charge and power boost control logic 106. Businterface circuitry 54 includes a charge inverter 54 a and power boostrectifier 54 b. Storage interface circuitry 64 includes charge rectifier64 a and power boost inverter 64 b. Transformer 58 is coupled betweencircuitry 54 and circuitry 64. Charge inverter 54 a and boost inverter64 b can be of an H-bridge type based on IGBTs, FETs (including MOSFETtype), gated thyristors, SCRs, or such other suitable gates/switchingdevices as would occur to those skilled in the art. Further, whilerectifiers 54 b and 64 a are each represented as being distinct from thecorresponding inverter 54 a or 64 b, in other embodiments one or more ofrectifiers 54 b and 64 a can be provided in the form of a full wave typecomprised of the protective “free wheeling” diodes electrically coupledacross the outputs of the respective inverter 54 a or 64 b component.For rectifier operation of this arrangement, the corresponding invertercomponents are held inactive to be rendered nonconductive.

Charge Proportional-Integral (PI) control circuit 52 is electricallycoupled to charge inverter 54 a and power boost PI control circuit 62 iselectrically coupled to power boost inverter 64 b. Circuits 52 and 62each receive respective charge and boost current references 106 a and106 b as inputs. Electrical current references 106 a and 106 b arecalculated by charge and power boost control logic 106 with processor100. These references are determined as a function of power demand,system power available, and the presence of any transient powerconditions. The total system power is in turn provided as a function ofthe power provided by power bridge 46 to bus 80 (inverter power), thepower-generating capacity of genset 30, and the power output capacity ofdevice 70. The inverter power corresponds to the AC electrical load“power demand” as indicated by the VAC voltage, IAC current, andcorresponding power factor that results from electrical loading of bus80. The genset power-generating capacity is determined with reference togenset power/load requested by logic 102. When the power demand on bus80 can be supplied by genset 30 with surplus capacity, then this surpluscan be used for charging device 70 by regulating converter 60 with PIcontrol circuit 52; and when the power demand exceeds genset 30capacity, supplemental power can be provided to bus 80 from device 70 byregulating converter 60 with PI control circuit 62. Various aspects ofdynamic “power sharing” operations of system 28 are further described inconnection with FIGS. 6 and 7 hereinafter; however, further aspects ofconverter 60 and its operation are first described as follows.

Converter 60 is controlled with system control logic 110 toenable/disable charge and boost operations. Under control of logic 110,the charge mode of operation and the boost mode of operation aremutually exclusive—that is they are not enabled at the same time. Whencharge mode is enabled, the electrochemical battery form of device 70 ischarged in accordance with one of several different modes depending onits charging stage. These charging stages may be of a standard type andmay be implemented in hardware, software, or a combination thereof. Inone form, a three-stage approach includes bulk, absorption, and floatcharging. When charging, circuit 52 outputs PWM control signals thatdrive gates of charge inverter 54 a in a standard manner. Typically, thePWM control signals are input to standard power drive circuitry (notshown) coupled to each gate input, and may be isolated therefrom byoptoisolators, isolation transformers, or the like. In response to thePWM input control signals, inverter 54 a converts DC power from DC bus44 to an AC form that is provided to rectifier 64 a of circuitry 64 viatransformer 58. Rectifier 64 a converts the AC power from transformer 58to a suitable DC form to charge battery device 75. In one form directedto a nominal 12 Vdc output of battery device 75, transformer 58 stepsdown the AC voltage output by inverter 54 a to a lower level suitablefor charging storage device 70. For nonbattery types of devices 70,recharging/energy storage in the “charge mode” is correspondinglyadapted as appropriate.

When power boost mode is enabled, boost PI control circuit 62 providesPWM control signals to boost inverter 64 b to control the powerdelivered from device 70. The circuit 62 output is in the form of PWMcontrol signals that drive gates of boost converter 64 b in a standardmanner for a transformer boost configuration. Typically, these controlsignals are input to power drive circuitry (not shown) with appropriateisolation if required or desired. When supplementing power provided bygenerator 32, a current-controlled power boosting technique isimplemented with circuit 62. Circuit 62 provides proportional-integraloutput adjustments in response the difference between two inputs: (1)boost current reference 106 b and (2) storage device 70 current detectedwith current sensor 76. In response, inverter 64 b converts DC powerfrom device 70 to an AC form that is provided to rectifier 54 b ofcircuitry 54 via transformer 58. Rectifier 64 b converts the AC powerfrom transformer 58 to a suitable DC form for DC bus 44. In one formdirected to a nominal 12 Vdc output of device 70, transformer 58 stepsup the AC voltage output from inverter 64 b, that is converted back toDC power for bus 44.

It should be appreciated that the DC voltage on DC bus 44 is variablerather than regulated. The variation in voltage on DC 44 as AC power issupplied to bus 80 extends over a wide range as the speed of genset 30and/or the boost power from or charge power to device 70 varies. In onepreferred embodiment, the lower extreme of this range is at least 75% ofthe upper extreme of this range while providing power to electricalloads on bus 80. In a more preferred form, the lower extreme is at least66% of the upper extreme. In an even more preferred form, the lowerextreme is at least 50% of the upper extreme.

Power bridge 46 can also be operated bidirectionally. Specifically, whenoptional shore power from source 90 is applied, it can be used to chargedevice 70 by converting the AC power waveform of shore power to DC poweron bus 44. FIG. 5 describes an AC to DC converter control system 304defined by control logic 104 and corresponding circuitry 304 a thatimplements charging with shore power through power bridge 46; where likereference numerals refer to like features. For system 304, sensor 46 aand 46 b provide power bridge 46 input VAC and IAC, respectively. VACand IAC are input to zero-crossing detector circuit 114 that is used todetermine the power factor of the shore power from source 90. This powerfactor is used to dynamically control bridge 46 during conversion ofshore power to DC power on bus 44. System 204 defines DC bus voltagefeedback loop 115 a, AC output voltage feedback loop 115 b, and ACoutput current feedback loop 115 c. Correspondingly, loops 115 a, 115 b,and 115 c include control operators 116 a, 116 b, and 116 c that applytransfer functions H_(v)(s), H_(vo)(s), and H_(io)(s); respectively.

Operator 116 a provides DC voltage feedback; operator 116 b provides ACvoltage feedback, and operator 116 c provides AC current feedback. Theoutput of operator 116 a is provided to the negative input of summationoperator 117 a. The positive input of summation operator 117 a receivesa DC voltage reference designated signal Vdcref. Summation operator 117a outputs the difference of the inputs as signal Verr that is input tocontrol operator 118 a. Operator 118 a applies the transfer functionG_(v)(s) and outputs signal Vvpi. Signal Vvpi is provided to multiplier117 b. Also, operator 116 b provides signal Vo as an input to multiplier117 b. The resulting product of Vvpi×Vo is provided to a negative inputof summation operator 117 c. The positive input of summation operator117 c receives the output of operator 116 c. The output of summationoperator 117 c is designated signal ierr, that is input to controloperator 118 b. Operator 118 b applies transfer function G_(i)(s) toproduce output the Vdrive signal to control the conversion of AC powerinput from source 90 to DC power on bus 44 with IGBTs 104 a of bridge46. It should be appreciated that control system 304 and correspondingoperators/logic can be implemented with hardware, software, firmware, ora combination of these.

The voltage feedback signal Vo from operator 116 b is used tosynchronize the waveform output. Power bridge 46 uses the single phaseH-bridge output stage bidirectionally with the inductor 47 a acting as aboost inductor for power factor control. The zero crossing circuit 114detects positive or negative waveforms with reference to neutral.Switching of IGBTs 104 a is performed based on the following: (a) IGBT Vand IGBT X switch on the positive-going sine wave, while the twofree-wheeling diodes 104 b provide boost with IGBT U and IGBT Y in theoff-state and (b) IGBT U and IGBT Y switch on the negative-going sinewave, while the two free-wheeling diodes 104 b provide boost with IGBT Vand IGBT X in the off-state. It should be appreciated that PIcontrollers 118 a and 118 b for both the voltage and the current couldbe of a different type (such as a Proportional-Integral-Derivative (PID)type, a Proportional (P) type, or a Proportional-Derivative (PD) type,to name just a few possibilities) and/or that a different method ofsinusoidal output waveform and/or power factor control could be utilizedas would be known to those skilled in the art.

FIG. 6 depicts power management process 120 for system 28 that isperformed in accordance with operating logic executed by processor 100;where like reference numerals refer to like features previouslydescribed. Also referring to FIGS. 1-5, process 120 begins withconditional 122 that tests whether shore power from external source 90is being applied. If the test of conditional 122 is true (yes) thenshore power operation 124 is performed. In operation 124, shore power isapplied from bus 80 to charge apparatus 170 as regulated by controlsystem 304. As explained in connection with FIG. 5, the AC shore powerfrom bus 80 uses inductor 47 a and circuit 46 to provide power factorcorrection, and is rectified through protective “free wheeling” diodeselectrically coupled across each gate of power bridge 46. The resultingDC voltage on bus 44 is regulated to a relatively constant value to theextent that the magnitude of the AC shore power on bus 80 remainsconstant. This DC voltage, as derived from shore power, is provided toconverter 60 to charge battery 75. During operation 124, shore power isalso provided to coach AC loads 84, to loads of inverter distribution 86through transfer switch 82, and to coach DC loads 74.

If the test of conditional 122 is false (no), process 120 continues withconditional 126. Conditional 126 tests whether system 28 is operating ina quite mode. If the test of conditional 126 is true (yes), then thestorage/battery only operation 128 is performed. Quite mode is typicallyutilized when the noise level resulting from the operation of genset 30is not permitted or otherwise not desired and when shore power is notavailable or otherwise provided. Correspondingly, in operation 128genset 30 is inactive, and power is provided only from storage device70. For operation in this quiet mode, power delivered by storage device70 is voltage-controlled rather than current-controlled, supplying agenerally constant voltage to DC bus 44 to facilitate delivery of anapproximately constant AC voltage on bus 80 of assembly 40. In one form,the AC power sourced from assembly 40 is only provided to loads forinverter distribution 86, with switch 82 being configured to preventpower distribution to coach AC loads 84. DC coach loads 74 are alsoserviced during operation 128.

Operator Input/Output (I/O) device 115 is operatively connected toprocessor 100 to provide various operator inputs to system 28 and outputstatus information. In one form, device 115 includes a keypad or otheroperator input control that selects/deselects “quiet mode” operation,turns system 28 on/off, provides for a preset automaticstarting/stopping time of system 28, one or more override commands,and/or directs other operational aspects of system 28. Device 115 alsoincludes one or more output devices such as a visual display, audiblealarm, or the like to provide information about the operation of system28, various presets or other operator-entered operating parameters, andthe like. In one nonlimiting form, device 115 is mounted in a cabin ofcoach 22 and is in communication with processor 100 in assembly 40 viaCAN interfacing.

If the test of conditional 126 is false (no), then conditional 130 isencountered. Conditional 130 tests whether power share mode is active.In response to changes in electrical loading of system 28, the powershare mode dynamically adjusts the speed of genset 30 and boost/chargeoperations based on total power capacity and transient status of system28. It should be appreciated that total power accounts for: (a) ac poweroutput from power bridge 46 as measured by inverter voltage and current,(b) the dc power as measured at the storage device, and (c) the powerloss intrinsic to inverter assembly 40. The loss calculation facilitatesdetermination of a target genset speed and boost rate for steady stateoperation, as further discussed in connection with operation 138.

If the test of conditional 130 is true (yes), then conditional 132 isexecuted. Conditional 132 tests whether a power level change ortransient has been detected during operation in the power share mode. Ifthe test of conditional 132 is true (yes), then transient handlingroutine 150 is performed as further described in connection with FIG. 7.If the test of conditional 132 is false (no), then the power is atsteady state in the power share mode. Steady state power delivery occursin one of two ways contingent on the steady state electrical loadmagnitude. Conditional 134 implements this contingency. Conditional 134tests whether the electrical load is below a selected threshold relatedto available genset 30 power (steady state genset rating). This testinvolves adding the dc and ac power levels, accounting for losses, andcomparing the total power to the genset power rating to determine ifsimultaneous charging of device 70 can be performed. If so, the test ofconditional 134 is true (yes) and operation 136 is performed.

In operation 136, a “genset plus charge” power share mode is supportedthat uses excess genset capacity for charging device 70, as needed(charge enabled/boost disabled). The genset plus charge power share modeof operation 136 typically reaches steady state from a transientcondition as further described in connection with routine 150. The totalgenset power in the genset plus charge mode is determined as themeasured ac power output plus the measured dc charging power lessestimated charger losses. In one form, the charger loss is estimated byreference to one or more tables containing the loss of the chargercircuitry as a function of battery voltage and charge current. Thetarget genset speed is then determined based on the normalized loadcalculated by the above method. The genset speed is set to support thedc and ac loads. When the genset reaches the rated charge level, itsspeed may be reduced. As the ac power requirement approaches the gensetrating, the charge rate may be reduced in order to maintain load supportwith genset 30.

If the test of conditional 134 is false (no), then operation 138results. In operation 138, genset 30 and device 70 are both utilized toprovide power to the electrical load at steady state in a “genset plusboost” power share mode. The desired boost rate is calculated based ontotal ac and dc power requirements less loss. This boost rate controlsboost current to reach the desired power share between the genset andthe storage device. The boost rate is calculated by determining thedesired storage power contribution to the system load and referencingone or more tables that represent the loss of boost circuitry as afunction of battery voltage and current. Typically, for this steadystate condition, genset 30 is operating at an upper speed limit withadditional power being provided from device 70 in the boost enabledmode. It should be understood that this genset plus boost power shareoperation also typically reaches steady state from a transient conditionas further described in connection with routine 150 as follows. In oneform, the load calculations are normalized to a percent system rating, apercent boost capability and a percent genset load to facilitate systemscaling for different genset and boost sizes. By way of nonlimitingexample, a few representative implementations include a 7.5 kW gensetand 2.5 kW boost for a total of 10 kW, a 5.5 kW genset and 2.5 kW boostfor a total of 8 kW, and 12 kW genset and 3 kW boost for a total of 15kW, and a 12 kW genset and 6 kW boost for a total of 18 kW. Naturally,in other embodiments, different configurations may be utilized.

FIG. 7 depicts transient handling routine 150 in flowchart form. Routine150 is executed by process 120 when conditional 132 is true (yes), whichcorresponds to a detected transient. As described in process 120 androutine 150, “transient” operation refers to a change in the electricalpower delivered by system 28 that typically results from a change inelectrical loading. In contrast, “steady state” operation refers to agenerally constant load level and corresponding constant level ofelectrical power delivered by system 28. For purposes of clarity,process 120 and routine 150 distinguishes these modes of operation at adiscrete logical level in a delineated sequence; however, it should beappreciated that implementation can be accomplished in a variety ofdifferent ways that may involve analog and/or discrete techniques withvarious operations performed in a different order and/or in parallel toprovide dynamic shifts between steady state and transient operations inresponse to electrical load conditions.

Routine 150 distinguishes between different types of power transientsbased on changes in one or more properties of the output power relativeto various thresholds. Further, as shown in the flowchart of FIG. 7,only transients corresponding to an increased power level are indicated(“positive” transients); however, it should appreciated that transientscorresponding to a decreased power level (“negative” transients) can behandled in a complimentary or different manner. Collectively, fourcategories of positive transients are distinguished by routine 150: typeI, type II, type III, and type IV that represent progressively smallerpower excursions/levels. Selected negative transient operations also aredescribed.

Routine 150 starts with conditional 152, which tests whether a type Itransient has occurred. A type I transient is the most extreme type oftransient power increase that typically corresponds to the addition of alarge reactive load, such as that presented by the inductive currentdraw of motors for multiple air conditioners 88 that are activated atthe same time, or when a resistive load exceeding the rating of thegenset is applied. To detect this type of load, the change in current ismonitored. An extremely large change in output current indicates a typeI transient. If the test of conditional 152 is true (yes), operation 154is performed that adjusts to the higher power level by immediatelydisabling charge mode (if applicable) and enabling the power boost modeat the maximum available power output level for device 70. At the sametime, genset 30 increases speed at its maximum available acceleration toaddress the transient. It should be appreciated that even with maximumacceleration, genset 30 will reach its maximum power generating capacitymore slowly than storage device 70. Provided that the target steadystate power level is less than the steady state power capacity of bothdevice 70 and genset 30 together (the system power capacity), then thelevel of power from device 70 decreases as genset speed increases tomaintain the required power level. This complimentary decrease/increaseof power from device 70/genset 30 continues until the maximum powercapacity of genset 30 is reached. For this type of transient, the steadystate power level typically remains greater than the capacity of genset30 alone, so supplemental power from storage device 70 is also provided.After transient type I handling by operation 154 is complete, routine150 returns to process 120. Absent any further transients, a steadystate power share mode follows under operation 138 when the steady statepower level is greater than the genset power capacity; however, shouldboost power not be required (a steady state power less than the powercapacity of genset 30), then the power share mode under operation 136results.

If the test of conditional 152 is false (no), then conditional 156 isexecuted. Conditional 156 tests for a type II transient. A type IItransient depends on the transient size in relation to current chargeand boost rates. In one form a type II transient results if its sizeexceeds the sum of the continuous boost rating and the current chargelevel. The type II transient can be further qualified with a powerfactor variable. For instance, in one implementation, if the powerfactor is lower than a selected threshold, the transient is classifiedas a type III instead of a type II transient. The type III transient isfurther discussed in connection with operation 166 hereinafter.

If the test of conditional 156 is true (yes), routine 150 proceeds toconditional 158 to determine if the type II transient is electricallyresistive as opposed to reactive. To identify a large reactive load fora type I transient in conditional 152, the current is checked forcertain extreme conditions on just a portion of an AC waveform cycle tohasten charge mode disable and boost mode enable (unless the boost modeis already active). In contrast, conditional 158 evaluates actual powerfactor based on a relatively longer portion of the AC waveform incorrespondence to less extreme transient criteria. Typically, two ACcycles are evaluated under the conditional 158 test. If the test ofconditional 158 is true (yes), then a resistive load type is indicatedand operation 160 is performed. In operation 160, required boost powerfrom device 70 and maximum acceleration of genset 30 are directed torapidly meet the transitory load demand. The steady state power levelremains greater than the capacity of genset 30 alone for a type IItransient, and so it is ordinarily supplemented with storage device 70.After transient type II handling by operation 160 is complete, routine150 returns to process 120. Absent any further transients, a steadystate power share mode results under operation 138 (steady statepower≧genset power capacity); however, should boost power not berequired at steady state (steady state power<the genset power capacity),then the power share mode at steady state continues under operation 136.If the test of conditional 158 is false (no), then operation 162 isperformed, which is described in greater detail below.

If the test of conditional 156 is false (no), then conditional 164 testsif a type III transient has taken place. If the test of conditional 164is true (yes), operation 162 is executed. In operation 162, boost powerfrom apparatus 170 is applied and genset speed is increased to meet thetarget power level subject to a rate of speed change limit as furtherdescribed hereinafter. For one embodiment, the boost circuitry isarranged to provide as much as twice its continuous rating duringtransients of a relatively short duration. This duration generallycorresponds to the amount of boost desired to support type I and type IItransients resulting from reactive loads subject to an initial inrushcurrent and to help engine 32 accelerate faster during large resistiveloads. For reactive loads, such as a single air conditioner 88, theduration is long enough to support the initial inrush of a low powerfactor load (like an air conditioner compressor motor) and allow for theslower ramp-up of generator speed. The resulting load after starting canbe less than the genset rating, which permits a slow ramp-up to thegenset final speed resulting in a final steady-state mode of genset pluscharge.

If the transient is resistive or otherwise of sufficient size such thatthe twice rated boost level cannot be maintained during a slow ramp,then the quick acceleration of the genset is desired. If the large loadis resistive, the final mode is genset plus boost, and the boost ratewill still decrease from its higher transient level to its maximumcontinuous rated level. Multiple air conditioners typically present sucha sufficiently large enough load to prompt immediate acceleration, asdescribed in connection with the type I transient of operation 154.

A type III transient corresponds to a power demand that can be handledby adding the required boost power to the already available power outputof genset 30. As the speed of genset 30 increases, the level of powerprovided by device 70 decreases to maintain a given power level. Fromoperation 162, routine 150 returns to process 120. If the steady statepower level is greater than or equal to the power capacity of genset 30,then the genset 30 runs at maximum capacity/speed and is supplemented bysupplemental power from storage device 70, resulting in the steady statepower share mode of operation 138. In contrast, if the steady statepower level is less than the genset power capacity, then the boost powergoes to zero and is disabled as genset 30 reaches a speed correspondingto the steady state power level. Under this circumstance, charge mode isenabled resulting in the steady state power share mode of operation 136.

If conditional 164 is false (no), then a default type IV transient isassumed. A type IV transient corresponds to a power change and thetarget post-transient steady-state level less than the power generatingcapacity of genset 30. Correspondingly, operation 166 is executed. Inoperation 166, the level of charging of device 70 in the charge mode isreduced and the genset speed is increased. As the genset share of thepower burden increases with its speed, the charge level can increaseuntil the power for electrical load(s) and charging collectively reachthe power generating capacity of genset 30, a maximum desired chargelevel is reached, or a desired power output of genset 30 results.

The genset speed increase in operation 162 and operation 166 is subjectto a selected acceleration limit that has a magnitude less than theacceleration of genset 30 in operations 154 and 160 in response to typeI and type II transients, respectively. Under certain situations,vibration and/or noise associated with the operation of a genset can bedistracting to a human user with nominal sensory and cognitivecapability—particularly in a parked vehicle. In some instances, thisdistraction can be reduced by using acoustic insulation, mechanicalisolators, or the like. Even so, genset operation may still present adistraction under certain conditions. It has been found that abruptchanges in genset speed typically are more noticeable than slower speedchanges. For the type III and IV transients of operations 162 and 166,the rotational speed of genset 30 is limited to a rate of changeselected to reduce human perception of genset operation that mightotherwise result from a more rapid increase in speed. It has been foundthat for typical motor coach and marine applications, load transientsare predominately of the type III or type IV transient. Accordingly, theapproach of routine 150 for such applications significantly reducessudden speed changes during normal use.

Typically, the acceleration limit in operation 162 and 166 issubstantially below the maximum acceleration available for genset 30. Inone preferred form, the selected rate of speed change limit is less thanor equal to 100 revolutions per minute (rpm) per second (100 rpm/s). Ina more preferred form, the selected rate of speed change limit is lessthan or equal to 50 rpm/s. In an even more preferred form, this limit isless than or equal to 20 rpm/s. In a most preferred form, the limit isapproximately 10 rpm/s. After the charge level and the genset speedstabilize for the type III or IV transient, routine 150 returns toprocess 120. In the absence of a further intervening transient, a steadystate power share mode results in operation 136 and/or operation 138,depending on the steady state power level relative to the powergenerating capacity of genset 30.

In response to a negative transient to a lower target power level in thepower share mode, the specific routine generally depends on the mannerin which power is being supplied prior to the negative transient. For aninitial steady state level provided with maximum boost power from device70 and maximum power output genset 30, a decrease to a value greaterthan or equal to the power generating capacity of genset 30 is providedby commensurately lowering the boost power output from device 70. For anegative transient from a steady state power level in operation 138 to asteady state power level in operation 136, power from boost modedecreases down to zero after which charge mode is enabled, and gensetspeed is decreased subject to a rate of change limit less than themaximum available deceleration, analogous to the limited acceleration ofgenset 30 in connection with operations 162 and 166. Accordingly, theboost power level decrease is slowed to maintain a given power level.Once charging is enabled, deceleration of genset 30 would typically stopat a speed desired to maintain steady state power to the load and toperform charging level at a desired level. For decreasing loadtransients from a steady state power plus charge mode, charging isincreased in response to the load reduction and/or genset speed isdecreased with the rate of speed decrease being subject to a selectedlimit less than the maximum deceleration available. During a negativetransient while boost is active, the boost rate can decrease by making astep change to a lower boost rate or disabling boost. If boost isdisabled, charging typically increases to a desired charge rate aspermitted by available capacity. As a result, genset 30 may run at afaster speed at steady state than required to sustain the resulting loadbecause of the desired charge level. While the engine speed is typicallyramped to reduce perception of a speed change during a negativetransient, such speed may be decreased at its maximum rate if thenegative transient is so large that it threatens to cause anunacceptably high voltage on DC bus 44. In one implementation, thisthreshold DC voltage is about 300 volts.

For type I-III transients, a typical sequence begins with the gensetplus charge mode initially, disabling the charge mode, enabling theboost mode with a desired level of boost, ramping up the genset to arequired speed that supports the final target AC load plus a desiredcharge load, decreasing the boost in conjunction with increasing thegenset speed until boost reaches zero then re-enabling charge mode,ramping up charge level as the genset continues to ramp up until thetotal system load (ac+dc) is supported by the genset. In cases where thetotal system load exceeds genset capacity then charge is reduced orboost is used to support the ac load instead.

In one implementation, the system continues to update the total systemload and update the boost and the target genset speed if additionaltransient events occur during the gradual acceleration of genset speedcaused by a type III or IV transient. If additional transient eventsoccur the transient may be reclassified as a type II or I transient andthe system will process per the correct classification. It should alsobe noted that in a typical motor coach or marine application the loadtransients often predominately result in a type III or type IVtransient. Generally, charging is enabled on a negative transient whenthe ac power becomes lower than the genset rated capacity, and thecharge rate ramps up to match the deceleration rate of the genset untilthe genset speed matches the total system load (ac+dc). Also, the gensetspeed may be decreased at its maximum rate if the negative transient issignificantly large enough to cause voltage on DC bus 44 to exceed anupper threshold. This limitation reduces the period of time (if any)that the DC bus 44 exceeds a desired upper level, such as 300 volts inone nonlimiting example.

Returning to process 120, operations 124, 128, 136, and 138 proceed toconditional 140. Conditional 140 tests whether to continue operation ofprocess 120. If conditional 140 is true (yes), process 120 returns toconditional 122 to re-execute the remaining logic. If conditional 140 isfalse (no), process 120 halts. It should be recognized that process 120and routine 150 are each symbolic logical representations of variousdependent and independent functions that could be embodied and/orimplemented in a number of different ways. For example, even thoughpresented in an ordered, sequential manner, various conditionals andoperations could be reordered, combined, separated, operated inparallel, and/or arranged in a different manner as would occur to oneskilled in the art. Such alternatives encompass analog and/or discreteimplementations. It should be recognized that in other embodimentsdifferent criteria could be used to detect transients and/or differenttransient responses could be provided. In one further embodiment,limiting acceleration and/or deceleration of genset 30 is not used atall or is subject to removal by operator command through operator inputcontrol and display 115. Alternatively or additionally, more or fewertransient types are recognized/detected and/or different criteria defineone or more of various transient types. In certain operation modes,charging may be decreased or eliminated to reduce genset speed at steadystate. Alternatively or additionally, boost power can be used in lieu ofgenset 30 at lower steady state power levels under the boost powercapacity of storage device 70. This operation could be subject to amonitored reserve power level of storage device 70. Boost power couldalso be used to reduce power that otherwise could be provided by genset30 to maintain genset 30 at a lower speed.

Many other embodiments of the present application exist. For example,one or more fuel cell devices, capacitive-based storage devices, and/ora different form of rechargeable electrical energy storage apparatuscould be used as an alternative or addition to an electrochemical cellor battery type of storage device 70. Furthermore, one or more fuelcells (including but not limited to a hydrogen/oxygen reactant type)could be used to provide some or all of the power from genset 30 and/orenergy storage device 70. Engine 32 can be gasoline, diesel, gaseous, orhybrid fueled; or fueled in a different manner as would occur to thoseskilled in the art. Further, it should be appreciated that engine 32 canbe different than a reciprocating piston, intermittent combustion type,and/or coach engine 26 can be used in lieu of engine 32 to providemechanical power to generator 34 or to supplement mechanical powerprovided by engine 32. In still another embodiment, the vehicle carryingsystem 28 is a marine vessel. In one variation of this embodiment,rotational mechanical power for generator 34 is provided from apropulsion shaft (such as a propeller shaft) with or without engine 32.Alternatively or additionally, generator 34 can be of a different type,including, but not limited to a wound field alternator, or the like withadaptation of circuitry/control to accommodate such different generatortype, as desired.

Another embodiment includes more than one rectifier/DC bus/invertercircuit to convert electricity from a variable speed generator to afixed frequency electric output. For one implementation, the generatoris constructed with two isolated three-phase outputs that each supplyelectricity to a different inverter circuit, but the same engine servesas the prime mover. When multiple rectifier/DC bus/inverter circuits areused in this manner, some or all may include a charge/boost circuitryoperating through the corresponding DC bus.

Still another embodiment includes more than one rectifier/DCbus/inverter circuit to convert electricity from a variable speedgenerator to a fixed frequency electric output. For one implementation,the generator is constructed with two isolated three-phase outputs thateach supply electricity to a different inverter circuit, but the sameengine serves as the prime mover. When multiple rectifier/DCbus/inverter circuits are used in this manner, some or all may include acharge/boost circuitry operating through the corresponding DC bus.

In another embodiment, as shown in FIG. 8, a system 200 includes aDC-to-AC inverter 202 to provide an AC electrical power output with anapproximately fixed frequency and voltage to one or more AC electricalloads 204. The system 200 includes a variable voltage DC bus 206 that ismaintained at a suitable level to provide an electrical energy input tothe inverter 202. Like DC bus 44, DC bus 206 is maintained within avoltage range suitable to provide for the operation of inverter 202, andfurther to provide energy to store and maintain electrical energy instorage device 214 at a suitable level. Converter 212 is configured toprovide suitable DC-to-DC conversion/transmission between bus 206 anddevice 214 as desired. Electric power is provided from device 214 to DCbus 206 via converter 212 when device 214 is being used as an electricalenergy source. In contrast, when electrical energy is stored by device214, electric power flows from DC bus 206 to device 214 via converter212.

FIG. 9 shows one embodiment of the first type of power source 208 in theform of a wind turbine power source 208 a that converts wind energy toelectrical energy. In one embodiment, source 208 a includes avariable-speed generator to convert mechanical energy resulting towind-driven rotation of the turbine into electricity while others maynot—instead having a different form of mechanical-to-electrical energyconversion. For a variable-speed generator configuration of source 208a, the wind turbine power source 208 a may provide a variable AC poweroutput and/or the electrical power output may be discontinuous—such aswhen suitable wind is not available to drive the corresponding turbine.Alternatively or additionally, the AC output of source 208 a may beadjustable. In one nonlimiting example, the pitch of the turbine bladesvaries to change speed and correspondingly adjust AC signal frequencyand the like.

FIG. 10 shows another nonlimiting embodiment of the first type of power208 in the form of solar power source 208 b. The solar power source 208b converts solar (“light”) energy into electricity through applicationof photovoltaics, generating heat input to a thermodynamic machine, orthe like. The power output from the solar power source 208 b may be ofan AC or DC type, or a combination of both. Alternatively oradditionally, the electrical output of source 208 b may be variable orgenerally fixed in correspondence to the particulars of thesolar-to-electric conversion technique(s) employed. It should beappreciated that source 208 may likewise be discontinuous given theintermittent nature of daylight hours.

The power conditioning electronics 210 are electrically coupled betweenthe first type of power source 208 and the variable voltage DC bus 206to provide electric power from the power output of the first type ofpower source 208. In one embodiment, the power conditioning electronics210 can include a rectifier to rectify an AC form of power input bysource 208 to a rectified DC form on bus 206. Such an arrangement can beapplicable when the first type of power source 208 is of the wind powersource 208 a form that includes a variable speed-generator output. Inanother embodiment, the power conditioning electronics 210 can include aDC-to-DC converter to convert a DC power output from source 208 to anappropriate level for bus 206. Such an arrangement can be applicablewhen the first type of power source 208 is of a solar power source 208 bform.

A second type of power source 216 generally supplies an AC power output.The second type of power source 216 may be an adjustable powergenerating device such as a variable speed generator driven by aninternal combustion engine. A rectifier 217 is electrically coupledbetween the second type of power source 216 and the variable voltage DCbus 206 to provide DC electric power rectified from the AC power output.Rectifier 217, Converter 212, and electronics 210 may include filters,limiters, protective devices/components, and/or other circuitry as wouldoccur to those skilled in the art to conform to desired operation.

Next, selected operational aspects of system 220 are provided inconnection with control circuitry 220. Control circuitry 220 detects achange in an AC power demand in the one or more AC electrical loads204—typically detecting corresponding electrical current flow changes,AC voltage fluctuation, and/or determining the corresponding AC powerfactor of the output of inverter 202. The control circuitry 220 isresponsive to the change in the AC power demand of the loads 204 andadjusts the DC electric power from the converter 212 such that storagedevice 214 provides power to or absorbs power from the DC bus 206 tomeet the changing AC power demand. The control circuitry 220 may alsomonitor a power output capacity of the first type of power source 208.Based on the power output capacity, the control circuitry 220 mayactivate or start the second type of power source 216 to provide powerto the DC bus 206 to meet the AC power demand of the one or more ACelectrical loads 204 when the power output capacity of the first type ofpower source 208 is less than the AC power demand. During the transitiontime as the second type of power source 216 is building-up to therequired power output, the storage device 214 provides the differencebetween the output power of the first type of power source 208 and thedemand 204. It is contemplated that the control circuitry 220 may alsoaccount for the power demand of one or more DC loads 222.

As previously indicated, system 200 includes another controllableconverter 212. Converter 212 is electrically coupled between the DC bus206 and one or more DC electrical loads 222 to provide DC electric powerthereto. Furthermore, the control circuitry 220 may monitor a DC powerdemand of the one or more DC electrical loads 222. Based on the DC powerdemand alone or in combination with the AC power demand, the controlcircuitry 220 adjusts the AC output power of the second type of powersource 208 to meet the DC power demand and/or the AC power demand.

In some embodiments, one or more first-type power sources 208 providebase load power to the system 200 where any difference between loaddemand and the first type of power source 208 is absorbed or deliveredby device 214. The power provided by or absorbed by device 214 isdynamically controlled by the control circuitry 220 with a resolutionsufficient to meet performance expectations.

The control circuitry 220 uses the difference calculation to deliver therequested power to the common DC bus 206 shared by one or morefirst-type power sources 208 and one or more power storage devices 214.As the power delivering capacity of the first type of power source 208changes, one or more second-type power sources 216 can be added to theDC bus 206 to maintain the power required by the loads (204 and/or 222).

In some embodiments, one or more second-type power sources 216 providebase load power in the system 200. Any difference between the loaddemand and the power output from second type of power source 216 isprovided or absorbed by a power storage device 214. The power providedby or absorbed by the power storage device 214 is dynamically controlledby the control circuitry 220.

The control circuitry 220 uses the difference calculation to deliver therequested power to the common DC bus 206 shared by one or moresecond-type power sources 216 and power storage device 214. During anelectrical load change, the second type of power source 216 changes itsload set point to move toward delivering the new load operating point.During the transition of source 216, the power storage device 214delivers or absorbs a variable amount of power to match system outputpower to the detected load requirements, as needed.

Yet another embodiment includes: rectifying AC output power from a powergenerating device to provide a variable amount of electric power to a DCbus; inverting DC electric power from the DC bus to provide AC electricpower to one or more AC electrical loads; measuring an AC power demandby the one or more AC electrical loads; determining a difference betweenthe AC output power from the power generating device and the AC powerdemand; and controlling a power storage device to provide power to orabsorb power from the DC bus based on the difference.

The embodiment may also include one or more features: based on thedifference, increasing, decreasing, or maintaining the AC output powerof the power generating device to meet the AC power demand of the one ormore AC electrical loads; monitoring the one or more AC electrical loadsto determine if the AC power demand has changed, and based on a changein the AC power demand, adjusting the AC output power of the powergenerating device to meet the AC power demand of the one or more ACelectrical loads; the power storage device does not provide power to orabsorb power from the DC bus when the difference is approximately zero;carrying a system including the power generating device, the powerstorage device, and the one or more AC electrical loads with a vehicle;charging the power storage device with DC power from the DC bus; andproviding DC power to one or more DC electrical loads connected to theDC bus, monitoring a DC power demand of the one or more DC electricalloads, and based on the DC power demand, adjusting the AC output powerof the power generating device to meet the DC power demand and the ACpower demand.

Another embodiment includes: an inverter to provide AC electrical powerto one or more electrical loads; a variable voltage DC bus electricallycoupled to the inverter to provide DC electric power to the inverter; apower generating device to supply a variable AC power output; arectifier electrically coupled between the power generating device andthe variable voltage DC bus to provide DC electric power rectified fromthe AC power output; a controllable converter electrically coupled tothe variable voltage DC bus and an electrical energy storage apparatuselectrically coupled to the controllable converter to provide DCelectric power to the variable voltage DC bus; a sensing arrangement todetect a change in a power demand in the one or more AC electricalloads; and control circuitry responsive to the change in the powerdemand to adjust the AC power output of the power generating device tomeet the AC power demand and to adjust the DC electric power from theconverter to provide power to or absorb power from the DC bus. The powergenerating device may be a genset 30 or a fuel cell or the like.

The embodiment may further include a vehicle carrying the inverter, DCbus, converter, power generating device, rectifier, sensing arrangement,and control circuitry. The power generating device may include avariable speed generator and means for adjusting a rotational speed ofthe generator. The energy storage apparatus may include at least onebattery. The control circuitry may include a processor with means fordynamically controlling power sharing between the power generatingdevice and the storage apparatus. The converter may be structured toselectively charge the storage apparatus with electric power from thepower generating device in response to one or more processing signalsfrom the control circuitry.

Another embodiment includes: rectifying AC output power from a firsttype of power source to provide electric power to a DC bus; inverting DCelectric power from the DC bus to provide AC electric power to one ormore AC electrical loads; measuring an AC power demand by the one ormore AC electrical loads; determining a difference between the AC outputpower from the first type of power source and the AC power demand;controlling a power storage device to provide power to the DC bus basedon the difference; monitoring a power output capacity of the first typeof power source; and providing power from a second type of power sourceto the DC bus to meet the power demand of the one or more AC electricalloads when the power output capacity of the first type of power sourceis less than the AC power demand.

The embodiment may include one or more of the following features:rectifying AC output power from the second type of power source toprovide electric power to the DC bus; monitoring the one or more ACelectrical loads to determine if the AC power demand has changed, andbased on a change in the AC power demand, adjusting the AC output powerof the second type of power source such that the electric power on theDC bus meets the AC power demand of the one or more AC electrical loads;wherein the power storage device does not provide power to or absorbpower from the DC bus when the difference is approximately zero;charging the power storage device with DC power from the DC bus;providing DC power to one or more DC electrical loads coupled to the DCbus through a converter, monitoring a DC power demand of the one or moreDC electrical loads, and based on the DC power demand, adjusting the ACoutput power of the second type of power source such that the electricpower on the DC bus meets the AC power demand and the DC power demand.

Yet another embodiment includes: an inverter to provide AC electricalpower to one or more AC electrical loads; a variable voltage DC buselectrically coupled to the inverter to provide DC electric power to theinverter; a first type of power source to supply a variable AC poweroutput; a first rectifier electrically coupled between the first type ofpower source and the variable voltage DC bus to provide DC electricpower rectified from the AC power output; a first controllable converterelectrically coupled to the variable voltage DC bus and an electricalenergy storage apparatus electrically coupled to the first controllableconverter to provide DC electric power to the variable voltage DC bus; asecond type of power source to supply a AC power output; a secondrectifier electrically coupled between the second type of power sourceand the variable voltage DC bus to provide DC electric power rectifiedfrom the AC power output; and control circuitry to detect a change in anAC power demand in the one or more AC electrical loads, the controlcircuitry being responsive to the change in the AC power demand toadjust the DC electric power from the converter to provide power to orabsorb power from the DC bus, wherein the control circuitry isstructured to monitor a power output capacity of the first type of powersource and start the second type of power source to provide power to theDC bus to meet the AC power demand of the one or more AC electricalloads when the power output capacity of the first type of power sourceis less than the AC power demand.

The embodiment may include one or more of the following features: asecond converter electrically coupled between the DC bus and one or moreDC electrical loads to provide DC electric power to the DC loads;wherein the first type of power source is selected from the groupconsisting of a generator driven by a wind turbine and solar power;wherein the second type of power source is selected from the groupconsisting of a variable speed generator driven by an internalcombustion engine and a fuel cell; and wherein the energy storageapparatus includes at least one battery.

A further embodiment includes: inverting DC electric power from a DC busto provide AC electricity to one or more electrical loads; rectifying ACpower output from a variable speed generator to provide a variableamount of electric power to the DC bus; measuring AC electric powerprovided to the one or more electrical loads; determining a powercontrol reference that changes with variation of a difference betweenthe AC electric power and capacity of the generator to provide power tothe DC bus; and adjusting DC electric power output from an electricalenergy storage device to the DC bus in response to change in the powercontrol reference.

Still another embodiment comprises: inverting DC electric power from aDC bus to provide AC electricity to one or more electrical loads;rectifying AC power from a variable speed generator to provide a firstvariable amount of electric power to the DC bus; detecting voltage andcurrent applied to the one or more electrical loads; determining a powercontrol reference as a function of the voltage and the current; andregulating DC power from an electrical energy storage device to providea second variable amount of electric power to the DC bus.

Yet a further embodiment is directed to a system, comprising: aninverter to provide AC electrical power to one or more electrical loads;a variable voltage DC bus electrically coupled to the inverter toprovide DC electric power to the inverter; a controllable converterelectrically coupled to the variable voltage DC bus and an electricalenergy storage apparatus electrically coupled to the controllableconverter to provide a first portion of the DC electric power to thevariable voltage DC bus; a variable speed generator to supply a variableAC power output; a rectifier electrically coupled between the variablespeed generator and the variable voltage DC bus to provide a secondportion of the DC electric power rectified from the AC power output; anda sensing arrangement to detect voltage and current provided to the oneor more electrical loads from the variable voltage DC bus. Controlcircuitry is also included that is coupled to the controllable converterand the sensing arrangement. The control circuitry is responsive to thevoltage and the current to generate a power control signal indicative ofa change in the AC electrical power provided to the one or moreelectrical loads, the controllable converter being responsive to thepower control signal to change the second portion of the DC electricpower provided to the variable voltage DC bus from the controllableconverter circuitry.

In another embodiment, an apparatus, includes: a variable speedgenerator; an electrical energy storage device; a DC bus coupled to thevariable speed generator and the electrical energy storage device; meansfor inverting DC electric power from the DC bus to provide ACelectricity to one or more electrical loads; means for rectifying ACpower output from the variable speed generator to provide a variableamount of electric power to the DC bus; means for measuring AC electricpower provided to the one or more electrical loads; means fordetermining a power control reference that changes with a differencebetween the AC electric power and capacity of the generator to providepower to the DC bus; and means for adjusting DC electric power outputfrom the electrical energy storage device to the DC bus in response tochange in the power control reference.

A further embodiment comprises a vehicle with a power generation system.This system includes: means for inverting DC electric power from a DCbus to provide AC electricity to one or more electrical loads; means forrectifying AC power from a variable speed generator to provide a firstvariable amount of electric power to the DC bus; means for detectingvoltage and current applied to the one or more electrical loads; meansfor determining a power control reference as a function of the voltageand the current; and means for regulating DC power from an electricalenergy storage device in response to this reference to provide a secondvariable amount of electric power to the DC bus.

Any theory, mechanism of operation, proof, or finding stated herein ismeant to further enhance understanding of the present invention and isnot intended to make the present invention in any way dependent uponsuch theory, mechanism of operation, proof, or finding. It should beunderstood that while the use of the word preferable, preferably orpreferred in the description above indicates that the feature sodescribed may be more desirable, it nonetheless may not be necessary andembodiments lacking the same may be contemplated as within the scope ofthe invention, that scope being defined by the claims that follow. Inreading the claims it is intended that when words such as “a,” “an,” “atleast one,” “at least a portion” are used there is no intention to limitthe claim to only one item unless specifically stated to the contrary inthe claim. Further, when the language “at least a portion” and/or “aportion” is used the item may include a portion and/or the entire itemunless specifically stated to the contrary. While the invention has beenillustrated and described in detail in the drawings and foregoingdescription, the same is to be considered as illustrative and notrestrictive in character, it being understood that only the selectedembodiments have been shown and described and that all changes,modifications and equivalents that come within the spirit of theinvention as defined herein or by any of the following claims aredesired to be protected.

What is claimed is:
 1. A method, comprising: rectifying AC output powerfrom a power generating device to provide a variable amount of electricpower to a DC bus; inverting DC electric power from the DC bus toprovide AC electric power to one or more AC electrical loads; measuringan AC power demand by the one or more AC electrical loads; determining adifference between the AC output power from the power generating deviceand the AC power demand; and controlling a power storage device toprovide power to or absorb power from the DC bus based on thedifference.
 2. The method of claim 1, further comprising: based on thedifference, increasing, decreasing, or maintaining the AC output powerof the power generating device to meet the AC power demand of the one ormore AC electrical loads.
 3. The method of claim 1, further comprising:monitoring the one or more AC electrical loads to determine if the ACpower demand has changed; and based on a change in the AC power demand,adjusting the AC output power of the power generating device to meet theAC power demand of the one or more AC electrical loads.
 4. The method ofclaim 1, wherein the power storage device does not provide power to orabsorb power from the DC bus when the difference is approximately zero.5. The method of claim 1, further comprising: carrying a systemincluding the power generating device, the power storage device, and theone or more AC electrical loads with a vehicle.
 6. The method of claim1, further comprising: charging the power storage device with DC powerfrom the DC bus.
 7. The method of claim 1, further comprising: providingDC power to one or more DC electrical loads connected to the DC bus;monitoring a DC power demand of the one or more DC electrical loads; andbased on the DC power demand, adjusting the AC output power of the powergenerating device to meet the DC power demand and the AC power demand.8. An apparatus, comprising: an inverter to provide AC electrical powerto one or more AC electrical loads; a variable voltage DC buselectrically coupled to the inverter to provide DC electric power to theinverter; a power generating device to supply a variable AC poweroutput; a rectifier electrically coupled between the power generatingdevice and the variable voltage DC bus to provide DC electric powerrectified from the AC power output; a controllable converterelectrically coupled to the variable voltage DC bus and an electricalenergy storage apparatus electrically coupled to the controllableconverter to provide DC electric power to the variable voltage DC bus; asensing arrangement to detect a change in a power demand in the one ormore AC electrical loads; and control circuitry responsive to the changein the power demand to adjust the AC power output of the powergenerating device to meet the AC power demand and to adjust the DCelectric power from the converter to provide power to or absorb powerfrom the DC bus.
 9. The apparatus of claim 8, further comprising: avehicle carrying the inverter, DC bus, converter, power generatingdevice, rectifier, sensing arrangement, and control circuitry.
 10. Theapparatus of claim 8, wherein the power generating device includes avariable speed generator driven by an internal combustion engine andmeans for adjusting a rotational speed of the generator.
 11. Theapparatus of claim 8, wherein the energy storage apparatus includes atleast one battery.
 12. The apparatus of claim 8, wherein the controlcircuitry includes a processor with means for dynamically controllingpower sharing between the power generating device and the storageapparatus.
 13. The apparatus of claim 8, wherein the power generatingdevice includes a fuel cell.
 14. A method, comprising: conditioningoutput power from a first type of power source to provide electric powerto a DC bus; inverting DC electric power from the DC bus to provide ACelectric power to one or more AC electrical loads; measuring an AC powerdemand by the one or more AC electrical loads; monitoring a power outputcapacity of the first type of power source; determining a differencebetween the power output capacity of the first type of power source andthe AC power demand; controlling a power storage device to provide powerto the DC bus based on the difference; and providing power from a secondtype of power source to the DC bus to meet the power demand of the oneor more AC electrical loads when the power output capacity of the firsttype of power source is less than the AC power demand.
 15. The method ofclaim 15, further comprising: rectifying AC output power from the secondtype of power source to provide electric power to the DC bus.
 16. Themethod of claim 14, further comprising: monitoring the one or more ACelectrical loads to determine if the AC power demand has changed; andbased on a change in the AC power demand, adjusting the AC output powerof the second type of power source such that the electric power on theDC bus meets the AC power demand of the one or more AC electrical loads.17. The method of claim 1, wherein the power storage device does notprovide power to or absorb power from the DC bus when the difference isapproximately zero.
 18. The method of claim 1, further comprising:charging the power storage device with DC power from the DC bus.
 19. Themethod of claim 1, further comprising: providing DC power to one or moreDC electrical loads coupled to the DC bus through a converter;monitoring a DC power demand of the one or more DC electrical loads; andbased on the DC power demand, adjusting the AC output power of thesecond type of power source such that the electric power on the DC busmeets the AC power demand and the DC power demand.
 20. An apparatus,comprising: an inverter to provide AC electrical power to one or more ACelectrical loads; a variable voltage DC bus electrically coupled to theinverter to provide DC electric power to the inverter; a first type ofpower source to supply a power output; power conditioning electronicselectrically coupled between the first type of power source and thevariable voltage DC bus to provide DC electric power conditioned fromthe power output; a first controllable converter electrically coupled tothe variable voltage DC bus and an electrical energy storage apparatuselectrically coupled to the first controllable converter to provide DCelectric power to the variable voltage DC bus; a second type of powersource to supply a AC power output; a rectifier electrically coupledbetween the second type of power source and the variable voltage DC busto provide DC electric power rectified from the AC power output; andcontrol circuitry to detect a change in an AC power demand in the one ormore AC electrical loads, the control circuitry being responsive to thechange in the AC power demand to adjust the DC electric power from theconverter to provide power to or absorb power from the DC bus, whereinthe control circuitry is structured to monitor a power output capacityof the first type of power source and activate the second type of powersource to provide power to the DC bus to meet the AC power demand of theone or more AC electrical loads when the power output capacity of thefirst type of power source is less than the AC power demand.
 21. Theapparatus of claim 20, further comprising: a second converterelectrically coupled between the DC bus and one or more DC electricalloads to provide DC electric power to the DC loads.
 22. The apparatus ofclaim 20, wherein the first type of power source includes a wind powersource.
 23. The apparatus of claim 20, wherein the first type of powersource includes a solar power source.
 24. The apparatus of claim 20,wherein the second type of power source includes a generator driven byan internal combustion engine.
 25. The apparatus of claim 20, whereinthe second type of power source includes a fuel cell.
 26. The apparatusof claim 20, wherein the energy storage apparatus includes at least onebattery.